Bronze stress relieving problems
I have been making some split bushings out of bronze and have had problems with the bushing stress relieving into an egg shape. I will briefly describe the process and please feel free to give your opinions or advice. I am using a 3.5 inch peace of round bronze to make a bushing with a 2 inch ID and 3 inch OD with a flange on each end. The finished result has to be perfectly round so I am making two, splitting off center, and then decking both down to size to make one finished pair. The problem I am having is the bushings are perfectly round and on size until they are split and decked and then the ears of the half circle are wanting to pull back into each other. making the 2 inch ID narrow at the entrance. any help is appreciated.
For bushes that size I do em like this.
Rough m/c the od profile & bore leaving .050 -.1 on all dims (not forgetting to allow for the split)
Split them with a slitting saw, make sure joint face is flat, tin and soft solder together - squeezing out as much solder as possible, carefuly reset on the centre line and bore to finished size, fit on mandrel and m/c OD , length etc.
heat to melt solder joint, clean solder off faces with sharp scraper.
I'm with Sami on this one. Rough the parts with plenty of stock, split, connect back together with special softjaws, hose clamp, crazy glue, finish bore and finish turn, separate.
Bronzes can be some of the most uncooperative materials. They clamp down on drills and reamers and are known to change shape when separated from the parent bar.
Let us know how you make out.
You don't have to do anything like this .Rough out id and od with extra allowance for finishing. Split the stock on bandsaw,mill faces flat,hold in 4 jaw with 2 jaws on each half
align split with surface guage and turn job, use some caution with depth of cut and feeds etc.When job is finished tape around outside with masking tape and then part it off.
Many types of equipment have split components by design,these are machined every day
with very little problem.It is pretty simple actually.
Your distortion is caused from chucking too tightly,I really could teach you this process
in no time,it's easy with the correct procedure.
You MUST use 4 jaw chuck ,you MUST not chuck over the split and away you go
No chucking pressure, on mandrel with hose clamp, custom holding rings Closed up a tad. Rounds up when cap is torqued.
Machining pictures by johnoder - Photobucket
Thin job (.078 wall) with flanges.